In some vehicle seats, a forward tiltable headrest which is forward tiltable from a using position by releasing a locking function is used. A headrest described in Japanese Patent Application Laid-Open No. 2006-87702 (Patent Literature 1) is known as this type of headrest.
The Patent Literature 1 discloses a vehicle seat device having a locking mechanism for fixing a head rest attached to the top of a seat back in a using position, and an unlocking mechanism for unlocking the locked state by the locking mechanism. The locking mechanism is provided with a locking plate attached to a rotary shaft of the head rest, and an engagement hook engaged with the locking plate. The unlocking mechanism is provided with an operation rod projecting from the top of the seat back toward the headrest (see the Abstract). Further, in the vehicle seat device in the Patent Literature 1, one locking mechanism is provided on the rotary shaft of the headrest. The locking mechanism is provided in the vicinity of one of two hinge parts provided at both ends of an insert stay of the headrest in the width direction (see FIG. 2).